1. Field of the Invention
The present invention relates to apparatus and methods for removing resist (photoresist) films, indispensable to photolithographic processes for making minute structures of semiconductor integrated circuits or the like.
2. Description of the Related Art
As techniques for removing resist films, presently known are ashing methods in which a resist film to be removed is ashed with oxygen plasma, and heating and dissolving methods in which a resist film to be removed is dissolved using an organic solvent, such as a phenol- or halogen-base organic solvent, with being heated at 90 to 130xc2x0 C., or using concentrated sulfuric acid and hydrogen peroxide. Any of these techniques requires a certain time, much energy and a specific chemical material for decomposing or dissolving the resist film. This was a strain on the photolithographic process. In spite of a great demand for new resist removing techniques to replace the above techniques by ashing or dissolving, developments of peeling techniques are yet few. As a representative of such peeling techniques, a new technique has been developed in which a peeling liquid newly developed and the peeling action of high-frequency supersonic waves are used. As such a peeling liquid, the peeling action of xe2x80x9can IPA-HzOz-base ingredient+salt such as fluoridexe2x80x9d has been appreciated.
It is an object of the present invention to provide resist film removing apparatus and methods in which resist films can be peeled off by using a change in physical properties and a change in structure of the resist films due to application of steam and ultraviolet rays, and thereby to realize breakaway from much resources/energy consumption type techniques, that is, to realize environment-symbiosis type techniques by which resist films can be removed independently of the quantity of energy and kinds of chemical solvents.
More specifically, the present invention is directed to removal of resist films by using a change in physical properties, such as softening, expansion, hydration, swelling, or solidification, or a change in structure, such as cross-linking, oxidation, or decomposition, of the resist films due to application of steam and ultraviolet rays. Additive ingredients for promoting such a change in quality may be selectively used.
In other words, the present invention is directed to removal of resist films by a timely cross-combination, a spatially proper cross-combination, a proper cross-combination on temperature, or a chemically proper cross-combination of all or some of means for (or process of) spraying steam, compressed water, or compressed carbonic acid gas onto a resist film, means for (or process of) adding a chemical ingredient to the steam or compressed water, means for (or process of) heating or cooling the substrate holding thereon the resist film, and means for (or process of) irradiating the resist film with ultraviolet rays.
The present inventors have taken up the following elemental techniques as subjects, and studied and developed them:
Change in quality of resist films by steam;
Chemical promotion of quality change of resist films; and
Promotion of quality change of resist films by irradiation with ultraviolet rays.
According to an aspect of the present invention, an apparatus for removing a resist film used in a lithographic process, comprises: means for bringing steam into contact with the resist film; and means for spraying steam onto the resist film, wherein the resist film is peeled off by an action of steam.
According to an aspect of the present invention, the resist film is peeled off with saturated or superheated steam at a temperature within the range of 70xc2x0 C. to 200xc2x0 C.
According to an aspect of the present invention, an apparatus for removing a resist film used in a lithographic process, comprises: means for spraying saturated steam onto the resist film, wherein the resist film is peeled off by an action of the saturated steam.
According to an aspect of the present invention, the temperature of the saturated steam at the target surface is within the range of 70xc2x0 C. to 100xc2x0 C.
According to an aspect of the present invention, steam containing an ingredient for promoting a change in quality of the resist film is brought into contact with and/or sprayed onto a surface of the resist film to peel the resist film.
According to an aspect of the present invention, the apparatus comprises a steam supply system including a subsystem for generating steam, a subsystem for heating steam, a subsystem for controlling the water quantity to be supplied and the heat amount for heating, and a subsystem for controlling the pressure of steam. The steam supply system is connected to an ultrapure water supply line for selectively supplying saturated or superheated steam at a temperature within the range of 70xc2x0 C. to 200xc2x0 C.
According to an aspect of the present invention, the steam supply system further includes a subsystem for switching lines between the ultrapure water supply line and a line for a solution containing an ingredient for promoting a change in quality of the resist film, and an injecting pump for the ingredient, so that steam containing the ingredient and steam not containing the ingredient can be switched over.
According to an aspect of the present invention, the apparatus further comprises an ultraviolet reactor including an ultraviolet lamp of a wavelength corresponding to a transmissive distance of not less than 10 mm to steam. The ultraviolet lamp is disposed in parallel with a substrate surface on which the resist film is formed. The substrate surface can be irradiated while and after the resist film is peeled off the substrate surface by the action of steam.
According to an aspect of the present invention, the apparatus further comprises a chamber provided with a system for taking in a substrate on which the resist film is formed and taking out the substrate off which the resist film has been peeled, a system for purging an atmosphere in the chamber, a system for discharging gas or liquid from the chamber, a system for introducing steam into the chamber, and a system for driving a steam spraying nozzle to move relatively to the substrate surface on which the resist film is formed, so as to sweep the substrate surface. The steam spraying nozzle sprays steam onto the substrate surface to peel the resist film off the substrate surface.
According to an aspect of the present invention, the chamber is further provided with a system for supplying carbonic acid gas from a gas bomb into the chamber, and a gas spraying nozzle for spraying carbonic acid gas onto the substrate surface rapidly to cool the resist film to be peeled off.
According to an aspect of the present invention, the apparatus further comprises a supply line for a liquid chemical for cleaning a substrate, connected to the steam supply system, wherein the substrate off which the resist film has been peeled is cleaned by irradiation with ultraviolet rays and spraying steam, and then dried by spraying superheated steam.
According to an aspect of the present invention, the apparatus further comprises a filter for filtering off pieces of the resist film having been peeled off a substrate and contained in a liquid being discharged, or a centrifugal separator for separating the pieces from the liquid, wherein the liquid from which the pieces have been removed is reused.
According to an aspect of the present invention, a method for removing a resist film used in a lithographic process, comprises steps of: bringing saturated or superheated steam into contact with the resist film; and spraying saturated or superheated steam onto the resist film, wherein the resist film is peeled off by an action of steam.
According to an aspect of the present invention, steam containing an ingredient for promoting a change in quality of the resist film is brought into contact with a surface of the resist film to peel the resist film.
According to an aspect of the present invention, in a method for removing a resist film used in a lithographic process, saturated steam is sprayed onto the resist film, and the resist film is peeled off by an action of the saturated steam.
According to an aspect of the present invention, the temperature of the saturated steam at the target surface is within the range of 70xc2x0 C. to 100xc2x0 C.
According to an aspect of the present invention, a substrate surface on which the resist film is formed, is irradiated with excimer ultraviolet rays of a wavelength corresponding to a transmissive distance of not less than 10 mm to steam, while and after the resist film is peeled off the substrate surface by the action of steam.
According to an aspect of the present invention, organic, metallic, and granular contaminants are removed from a substrate surface off which the resist film has been peeled, by spraying steam with irradiating the substrate surface with ultraviolet rays, and then the substrate surface is cleaned and dried by spraying steam.
According to an aspect of the present invention, steam containing an ingredient for promoting a change in quality of the resist film is brought into contact with and/or sprayed onto a surface of the resist film to peel the resist film.
According to an aspect of the present invention, an apparatus for removing a resist film used in a lithographic process, comprises: means for making steam act on the resist film, wherein the resist film is peeled off by the action of the steam.
According to an aspect of the present invention, the steam is saturated steam, and the temperature of the saturated steam at the target surface is within the range of 70xc2x0 C. to 100xc2x0 C.
According to an aspect of the present invention, steam containing an ingredient for promoting a change in quality of the resist film is made to act on a surface of the resist film to be peeled off.
According to an aspect of the present invention, the apparatus further comprises at least one of: means for making water act on the resist film; means for making vapor of isopropyl alcohol act on the resist film; means for making compressed carbonic acid gas act on the resist film; means for adding a chemical ingredient into the steam and/or the water; means for irradiating the resist film with ultraviolet rays; means for applying high-frequency supersonic waves to the resist film; and means for cooling a substrate on which the resist film is formed, wherein the resist film is peeled off by properly cross-combining at least one of time and/or spatial conditions, conditions on temperature, and physical and/or chemical conditions for operating each of the means.
According to an aspect of the present invention, the apparatus further comprises a one-by-one process chamber in which substrates to be processed are disposed one by one. The chamber is provided with a system for taking in and out the substrates, a system for purging the atmosphere in the chamber, and a system for discharging gas or liquid from the chamber, in addition to the above means. The chamber is further provided with a driving system for at least one of the means for making steam act on the resist film, the means for making water act on the resist film, and the means for making compressed carbonic acid gas act on the resist film, to move relatively to the front or back surface of each substrate.
According to an aspect of the present invention, as the above time and/or spatial conditions for operating the above means and/or the above systems, the order of the operations and the intervals of the operations are properly cross-combined in relation to the portions subjected to the operations, i.e., the surface of the resist film, both or one of the front and rear surfaces of the substrate, or part of the front or rear surface of the substrate.
According to an aspect of the present invention, as the above conditions on temperature for operating the above means and/or the above systems, process temperatures and the raising and lowering speeds thereof are properly cross-combined in relation to the portions subjected to the operations, i.e., the surface of the resist film, both or one of the front and rear surfaces of the substrate, or part of the front or rear surface of the substrate.
According to an aspect of the present invention, as the above physical and/or chemical conditions for operating at least one of the means for adding a chemical ingredient into the steam and/or the water, the means for irradiating the resist film with ultraviolet rays, and the means for applying high-frequency supersonic waves to the resist film, the compositions of chemical ingredients for the steam and/or the water, the frequencies of supersonic waves, and the wavelengths of ultraviolet rays are properly cross-combined.
According to an aspect of the present invention, the above time and/or spatial conditions, the above conditions on temperature, and the above physical and/or chemical conditions are properly cross-combined with one another.
According to an aspect of the present invention, the means for making steam act on the resist film has the function of bringing the steam into contact with the resist film and the function of spraying the steam onto the resist film. The contact process and the spraying process are properly cross-combined.
According to an aspect of the present invention, the means for making steam act on the resist film has the function of making saturated steam act on the resist film and the function of making superheated steam act on the resist film. The saturated steam process and the superheated steam process are properly cross-combined.
According to an aspect of the present invention, the steam process by the means for making steam act on the resist film, and a chemical ingredient composition determined by the means for adding a chemical ingredient into the steam are properly cross-combined.
According to an aspect of the present invention, the steam process by the means for making steam act on the resist film, and the water spraying process by the means for making water act on the resist film are properly cross-combined.
According to an aspect of the present invention, the steam process by the means for making steam act on the resist film, and the ultraviolet irradiation process by the means for irradiating the resist film with ultraviolet rays are properly cross-combined.
According to an aspect of the present invention, the steam process by the means for making steam act on the resist film, and the high-frequency supersonic application process by the means for applying high-frequency supersonic waves to the resist film are properly cross-combined.
According to an aspect of the present invention, the steam process by the means for making steam act on the resist film, and the compressed carbonic acid gas spraying process by the means for making compressed carbonic acid gas act on the resist film are properly cross-combined.
According to an aspect of the present invention, the steam process by the means for making steam act on the resist film, and the cooling process by the means for cooling a substrate on which the resist film is formed, are properly cross-combined.
According to an aspect of the present invention, the steam process by the means for making steam act on the resist film, and the vapor process by the means for making vapor of isopropyl alcohol act on the resist film are properly cross-combined.
According to an aspect of the present invention, the compressed carbonic acid gas spraying process by the means for making compressed carbonic acid gas act on the resist film, and the ultraviolet irradiation process by the means for irradiating the resist film with ultraviolet rays are properly cross-combined.
According to an aspect of the present invention, by properly cross-combining the above time and/or spatial conditions, the above conditions on temperature, and the above physical and/or chemical conditions for operating the above means and/or the above systems, the substrate surface off which the resist film has been peeled is processed to remove residues of the resist film and alien substances. The substrate surface is thereby purified.
According to an aspect of the present invention, a method for removing a resist film used in a lithographic process, comprises a step of making steam act on the resist film, wherein the resist film is peeled off by the action of the steam.
According to an aspect of the present invention, the method further comprises at least one of: a step of making water act on the resist film; a step of making vapor of isopropyl alcohol act on the resist film; a step of making compressed carbonic acid gas act on the resist film; a step of adding a chemical ingredient into the steam and/or the water; a step of irradiating the resist film with ultraviolet rays; a step of applying high-frequency supersonic waves to the resist film; and a step of cooling a substrate on which the resist film is formed, wherein the resist film is peeled off by properly cross-combining at least one of time and/or spatial conditions, conditions on temperature, and physical and/or chemical conditions for performing each of the steps.
According to an aspect of the present invention, as the above time and/or spatial conditions for performing the above steps, the order of the steps and the intervals of the steps are properly cross-combined in relation to the portions subjected to the steps, i.e., the surface of the resist film, both or one of the front and rear surfaces of the substrate, or part of the front or rear surface of the substrate.
According to an aspect of the present invention, as the above conditions on temperature for performing the above steps, process temperatures and the raising and lowering speeds thereof are properly cross-combined in relation to the portions subjected to the steps, i.e., the surface of the resist film, both or one of the front and rear surfaces of the substrate, or part of the front or rear surface of the substrate.
According to an aspect of the present invention, as the above physical and/or chemical conditions for performing at least one of the step of adding a chemical ingredient into the steam and/or the water, the step of irradiating the resist film with ultraviolet rays, and the step of applying high-frequency supersonic waves to the resist film, the compositions of chemical ingredients for the steam and/or the water, the frequencies of supersonic waves, and the wavelengths of ultraviolet rays are properly cross-combined.
According to an aspect of the present invention, the above time and/or spatial conditions, the above conditions on temperature, and the above physical and/or chemical conditions are properly cross-combined with one another.
According to an aspect of the present invention, the step of making steam act on the resist film includes a sub-step of bringing the steam into contact with the resist film and a sub-step of spraying the steam onto the resist film. The contact process and the spraying process are properly cross-combined.
According to an aspect of the present invention, the step of making steam act on the resist film includes a sub-step of making saturated steam act on the resist film and a sub-step of making superheated steam act on the resist film. The saturated steam process and the superheated steam process are properly cross-combined.
According to an aspect of the present invention, the steam process by the step of making steam act on the resist film, and a chemical ingredient composition determined in the step of adding a chemical ingredient into the steam are properly cross-combined.
According to an aspect of the present invention, the steam process by the step of making steam act on the resist film, and the water spraying process by the step of making water act on the resist film are properly cross-combined.
According to an aspect of the present invention, the steam process by the step of making steam act on the resist film, and the ultraviolet irradiation process by the step of irradiating the resist film with ultraviolet rays are properly cross-combined.
According to an aspect of the present invention, the steam process by the step of making steam act on the resist film, and the high-frequency supersonic application process by the step of applying high-frequency supersonic waves to the resist film are properly cross-combined.
According to an aspect of the present invention, the steam process by the step of making steam act on the resist film, and the compressed carbonic acid gas spraying process by the step of making compressed carbonic acid gas act on the resist film are properly cross-combined.
According to an aspect of the present invention, the steam process by the step of making steam act on the resist film, and the cooling process by the step of cooling a substrate on which the resist film is formed, are properly cross-combined.
According to an aspect of the present invention, the steam process by the step of making steam act on the resist film, and the vapor process by the step of making vapor of isopropyl alcohol act on the resist film are properly cross-combined.
According to an aspect of the present invention, the compressed carbonic acid gas spraying process by the step of making compressed carbonic acid gas act on the resist film, and the ultraviolet irradiation process by the step of irradiating the resist film with ultraviolet rays are properly cross-combined.
According to an aspect of the present invention, by properly cross-combining the above time and/or spatial conditions, the above conditions on temperature, and the above physical and/or chemical conditions for performing the above steps, the substrate surface off which the resist film has been peeled is processed to remove residues of the resist film and alien substances. The substrate surface is thereby purified.
According to the present invention, by using a change in physical properties (such as swelling) of a resist film by steam and a light decomposition effect by ultraviolet rays, it becomes possible to peel off the resist film easily and surely. As a result, breakaway from much resources/energy consumption type techniques can be realized, that is, an environment-symbiosis type technique independent of the quantity of energy and kinds of chemical solvents can be realized.